Multiphysics modeling of environment assisted cracking of buried pipelines in contact with solutions of near-neutral pH

Abstract

This paper presents a multiphysics model to predict environment assisted cracking in buried pipelines exposed to near-neutral pH solutions. In the calculation of crack growth rates, we involve two main cracking modes: hydrogen-facilitated fatigue and hydrogen-facilitated anodic dissolution. The former is fully coupled under the hydrogen-enhanced localized plasticity theory with a focus on hydrogen embrittlement produced by hydrogen diffusion and trapping. This provides formalism to account for contributions of electrochemical corrosion and variation of mechanically-diffusive hydrogen on the crack growth rates. The latter is explicitly quantified using the high-resolution crack tip fields. A competitive-based model is employed to evaluate crack growth rates. The model is verified by comparing experimentally measured and numerically simulated crack growth rates of a full-scale test reported in the literature. The results of this investigation show that the effect of hydrogen on the anodic-dissolution results in conservative predictions of the crack growth rates.